Detection and Genetic Diversity of Human Metapneumovirus in Hospitalized Children with Acute Respiratory Infections in Southwest China
Division of Immunology, Children's Hospital of Chongqing Medical University, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing International Science and Technology Cooperation Center for Child Development and Disorders, Chongqing, China.Journal of clinical microbiology (Impact Factor: 3.99). 06/2012; 50(8):2714-9. DOI: 10.1128/JCM.00809-12
Human metapneumovirus (hMPV) is the main pathogen causing respiratory tract infection in susceptible populations, particularly in children and the elderly. Specimens were collected from hospitalized children with acute lower respiratory tract infections (ALRTI), and the hMPV was detected by using real-time reverse transcription-PCR (RT-PCR). The full-length G gene of hMPV was amplified by RT-PCR. A total of 1,410 nasopharyngeal aspirates (NPAs) were collected from April 2008 to March 2011, and 114 (10.2%) were positive for hMPV. Most hMPV-positive children were <5 years of age. The hMPV infection rate peaked in the spring-summer season of 2008 to 2009 and 2009 to 2010, while hMPV circulated predominantly during the winter-spring season of 2010 to 2011. The full-length G gene of 23 hMPV strains was amplified, and group A and B viruses accounted for 95.7% (22/23) and 4.3% (1/23), respectively. Genotype A2b of hMPV appeared to be predominant during the study period. Three genotypes (A2b, A1, and B1) were prevalent in the epidemic season of 2008 to 2009, and only genotype A2b was identified in the other two seasons (2009 to 2010 and 2010 to 2011). The G gene of hMPV was predicted to encode proteins with four different lengths, in which one with 210 amino acids was first identified in China. These findings suggest that hMPV was an important pathogen of ALRTI in pediatric patients, especially those <5 years of age. Genotype A2b of hMPV likely predominates in Southwest China, where other genotypes also circulate.
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ABSTRACT: Background: Human metapneumovirus (hMPV), which has a global distribution, is an important cause of acute respiratory tract infections, especially in children and immunocompromised patients. Methods: We investigated the genetic variability of partial nucleoprotein (N) gene sequences of hMPV strains identified among young children in South India. The sequences of the N gene were compared with previously reported sequences available in the GenBank repository. Results: The results showed that strains are localized in a geographically circumscribed area (topotype). The results also demonstrates that viruses from the same genetic lineage can circulate concurrently within a given location during a given season. The close clustering of the majority of our hMPV isolates indicates that the N gene sequences in the virus population are relatively homogeneous, and suggests temporal rather than geographic variations in the evolutionary pattern. In our study, the majority of the strains belonged to genetic lineage B2 (71.1 %), followed by A2b (18.4 %), A2a (7.9 %), and B1 (2.6 %), demonstrating the presence of 4 of the 5 known genotypes of hMPV. Global alignment of the nucleotide sequences showed that the strains are closely related to sequences from Canada, The Netherlands, and Australasia. Differences at the nucleotide level and the amino acid level were identified. The results provide evidence for the diversity of the N gene of hMPV in samples collected from South India compared with global strains. When investigated for selective pressure, the sequences showed 1 positively selected site and 19 negatively selected sites. Conclusion: These data should prove useful in further investigations of the evolutionary dynamics of hMPV infection.
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ABSTRACT: BACKGROUND: Respiratory syncytial virus (RSV) is the most important cause of serious respiratory infections in young children. No prior studies using molecular techniques to examine RSV transmission in the community childcare setting have been performed. OBJECTIVES: We seek to characterize the molecular epidemiology of RSV transmission in childcare to evaluate the impact of RSV disease in a community-based population. METHODS: We sequenced RSV-positive nasopharyngeal samples from a prospective longitudinal study of respiratory illnesses among children enrolled in childcare during three winter seasons. Phylogenetic analysis was performed to identify unique viral strains. RESULTS: RSV was detected in 59 (11%) illnesses. Compared to RSV-negative illnesses, RSV-positive illnesses were associated with longer symptom duration and increased frequency of health care visits. Another respiratory virus was detected in 42 (71%) RSV-positive illnesses. RSV viral load did not differ between RSV-positive illnesses with and without another respiratory virus identified (P=0.38). In two childcare rooms, 50% of the children had RSV detected within six days of the first case. Five (38%) of 13 illness episodes from one childcare room were sequenced and shown to be the same viral strain, suggesting rapid child-to-child transmission within the room over a 16 day period. CONCLUSIONS: RSV is rapidly transmitted within childcare. Childcare facilities may serve as ideal sites for evaluation of new prevention strategies given the high burden of RSV disease in this population and the rapidity of RSV spread between children.
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ABSTRACT: Human metapneumovirus (HMPV) is an important respiratory virus implicated in respiratory infections. The purpose of this study was to develop a one-step real-time RT-PCR assay that can detect all four lineages of HMPV and to identify the HMPV lineages circulating in Pune, India. Conserved regions of the nucleoprotein gene were used to design real-time primers and a probe. A total of 224 clinical samples that were positive for different respiratory viruses (including 51 samples that were positive for HMPV) were tested using the real time RT-PCR assay, and the specificity of the assay was observed to be 100 %. Using in vitro-synthesized RNA, the sensitivity of the assay was ascertained to be 100 copies of the target gene per reaction. Phylogenetic analysis of the nucleoprotein (N) and attachment glycoprotein (G) genes confirmed that this assay detected all lineages of HMPV. A2, B1 and B2 strains were observed during the study period. Our assay is highly sensitive and specific for all known lineages of HMPV, making it a valuable tool for rapid detection of the virus. A2 and B2 were the predominant subtypes circulating in Pune, Western India.